1. Field of the Invention
The present invention relates generally to a portable dewatering system, more specifically to a positive pressure, conditioned drying gas, gravity operated, dewatering system for hydraulic fluids, lubricating fluids, and petroleum based fluids like diesel fuel and the like.
2. Description of Related Art
Many lubricating fluids, petroleum based fluids such as hydraulic fluid, lubricating fluids, diesel fuel, bio-diesel fuel and the like, may need to be dewatered (remove or decrease the water content) to improve the relative performance or efficiency of the fluid and to reduce component damage. Petroleum based, also called hydrocarbon based, hydraulic fluids are the most common fluids for hydraulic systems. The difference between petroleum based hydraulic fluid and straight oil is generally the additives in the operating fluid. Hydraulic fluid also includes phosphate esters, which are somewhat fire resistant and generally allow for higher operating temperatures while providing lubrication qualities equal to petroleum based hydraulic fluids. Hydraulic fluid also includes synthetics fluids and synthetic blends that are usually phosphate esters, chlorinated hydrocarbons or a blend.
In hydraulic systems excess free or dissolved water can cause damage to sensitive or precision tolerance components. Under high pressure that is typical in hydraulic systems, water under compression can turn to steam causing cavitations damage, improper performance and degradation of the operating fluid.
For example, it is essential that the fuel used in fuel injected internal combustion engines and jet engines be free of water, algae, and other contaminates. When fuel is stored in bulk, such as in vehicle, boat, and aircraft fuel tanks, water droplets condensed from the atmosphere will form inside the fuel storage tanks and their ventilation pipes. The accumulation of this condensation, and possible microbial growth, will eventually be ingested by the engine fuel pick-up tubes, and carried along with the fuel to the engine fuel filtration system. In the case of ships at sea and aircraft as they encounter turbulent and rough conditions, the accumulated condensation at the fuel water interface moves about the storage tank so as to be easily ingested in quantities large enough to totally fill or saturate the engines filtration system causing the engine to stop.
In order to address these needs there have been developed a number of dewatering systems. The dewatering systems commercially available, and those only proposed in the literature, can fall into several broad classes. The present invention is only directed to the dewatering of hydraulic fluid, lubricating fluids, petroleum based fluids and the like. In these areas the dewatering systems can also be referred to as dehydrating systems and these terms can be used interchangeably throughout. Each of these terms, individually, however, are also commonly used in some water removal systems for very far removed applications from the present field. For example “dewatering systems” also reference sludge dewatering systems in waste water purification systems (i.e. sewage treatment); and “dehydration systems” also reference a class of food processing equipment.
As noted above the present invention is directed to the dewatering of “industrial fluids” such as hydraulic fluid, lubricating fluids, petroleum based fluids and the like. Within the meaning of this application the phrase “Industrial Fluid” includes petroleum based fluids, phosphate ester based fluids, and synthetics wherein water is removed or reduced from the fluid leaving the industrial fluid behind.
One class of industrial fluid dewatering system is an industrial fluid centrifugal separation system that can be used to separate out the water from the subject industrial fluid and the water drawn off. This requires a centrifuge for operation which limits the throughput and there is a question of how this operation affects the efficiency of the subject industrial fluid following the separation process. Representative examples of this technology can be found manufactured by Auxill Nederland BV which supplies devices using several centrifugal techniques, each with their specific utilization.
A second class of industrial fluid dewatering systems is based upon gravity separation of fluids, such as described in U.S. Pat. No. 6,042,722. This patent, which is included herein by reference in its entirety, discloses an apparatus for separating water contaminants from a fuel which has a specific gravity which is lower than that of water. The patent discloses that contaminated fuel is drawn from a bottom of a tank and passed into a separator, wherein the water stays at the bottom of the separator and is drained off. The patent notes that the fuel is forced upwardly from which any droplets of water flow along collector plates and fall to the bottom of the separator. The patent then notes that the fuel is passed through a filter which removes any particles of matter then the fuel is directed back to the tanks. The patent notes that the process can be repeated for as many times as necessary to cleanse the fuel of water and contaminates.
Industrial fluid dewatering systems can utilize coalescing technology to separate two mixed fluids. In a system using coalescing technology a porous barrier is presented that presents a greater flow resistance to one fluid, generally the contaminant, than it does the other. The fluid that experiences the greatest resistance will slow down or even stop and as this occurs smaller droplets come together forming larger ones. These eventually collect in globules large enough to settle or to form a surface layer. The agglomeration of smaller droplets to form larger ones is the definition of coalescence.
The “gravity based” industrial fluid dewatering systems in which the specific gravity difference between water and the industrial fluid being treated is used to run the system are distinguished from gravity “operated” industrial fluid dewatering systems in which gravity is used to move the industrial fluid to be cleaned through a cleaning chamber or process. The present invention, and most vacuum based systems, are gravity operated within the meaning of the present application, but are not “gravity based”
A further class of industrial fluid dewatering systems is filtration systems using water absorbing filters, but large scale water removal utilizing water absorbing filters is inefficient as these types of filters can only remove free water and some loosely emulsified water from industrial fluids. Water absorbent filters remove free and some emulsified water by super absorbent polymers impregnated in the media of the filter cartridge. The water is absorbed by the polymer, causing it to swell, and remains trapped in the filtration medium. Super absorbent filters can remove only a limited volume of water before causing the filter to go into pressure drop induced bypass. They are not well-suited for removing large volumes of water, but are a convenient method to maintain dry conditions in industrial systems that don't normally ingest a lot of water. These filters do not remove dissolved water from the industrial fluid.
Vacuum dewatering systems, also called vacuum dehydrators, is another class of industrial fluid dewatering system and can be classified as a mass transfer based industrial fluid dewatering system. Vacuum dehydrators have the advantage of being able to separate free, emulsified and dissolved water. See for example the industry leading industrial fluid vacuum dewatering or vacuum dehydrating systems manufactured by Schroeder Industries LLC under the SVD brand name. The SVD brand unit, when connected to a hydraulic reservoir of a system with wet industrial fluid, will draw the industrial fluid into a chamber where the fluid cascades down in a reactor chamber. Water is separated in the form of vapor and is removed by the vacuum pump. The vapor can be released to the atmosphere or condensed in a separate reservoir. The dewatered industrial fluid is pumped from the reactor chamber back to the system reservoir at a continuous flow rate. Further details of this system and technology can be found using the keyword “SVD” at the website www.schroederindustries.com.
Another class of industrial fluid dewatering systems is a high vacuum/heat purifiers flash distillation process which utilizes higher vacuum and temperature conditions inside a chamber, as compared to the vacuum dehydrators, to rapidly boil off water and other volatile materials from the industrial fluid. Flash distillation type equipment is often operated at vacuum and temperature conditions that are well within the vapor phase region of the industrial fluid for faster removal of water. The vacuum and temperature levels are more severe, wherein vacuum levels of >26 “Hg and temperatures >160° F. are commonly used in these equipment. Vapor condensers are often used to remove the vapors before they get to the vacuum pump. By virtue of higher vacuum and temperature levels, these units can offer higher water removal efficiencies for each pass of the industrial fluid compared with that of the mass transfer—vacuum dehydration type purifiers, but they also expose the fluid to higher thermal stresses in the process. Further, these systems require the creation and maintaining of high vacuum conditions.
The described uses of the above identified industrial fluid dewatering systems can represent challenging operational environments for such systems. For example, onboard ships, space is typically at a premium and the industrial fluid dewatering system must accommodate this restricted environment. Further, in such environments, mobile or portable units are often employed at periodic intervals, rather than permanent on board units. The portable applications require a portable system to fit through restricted access hatches, which can be on the order of 600 mm (about 24”).
As a representative example, consider a submarine application (a submarine is a type of ship within the meaning of this application) which will typically have 600 mm hatches and minimal equipment loading capabilities in many passageways (e.g. only a hand operated winch may be available for assisting in the raising and lowering of equipment through a hatch between levels). Further, some ship operating protocols require such portable equipment to be capable of being manually loaded and unloaded, which will further restrict the weight of the associated system. These size and weight restrictions make many of the prior art industrial fluid dewatering systems impractical and will severely limit the throughput of industrial fluid dewatering systems of the prior art that are sized to accommodate these operational restrictions. A low throughput industrial fluid dewatering system can quickly become impractical for many applications.
Within the meaning of this application, the terms portable and mobile are interchangeable and reference a system that is designed to be transported or moved into operating position. Within the meaning of this application, the phrase “hatch accessible” references a system that is designed to be transported or moved, in whole or in part, through a 600 mm hatch opening. Within the meaning of this application, the phrase “manually loadable” references a system that is designed such that each loadable component of the system is less than about 115 kgs (about 250 lbs).
The phrase “high through put” is a relative description when referencing a system that is designed to operate by processing at a given liters/hour rate of industrial fluid. Similarly, a “low” through put system is a relative description that references a system that is designed to operate or process less liters/hour of industrial fluid than a high throughput system of similar size. All of the systems are generally scalable unless there are operating restrictions, such as hatch accessibility or other space concerns, whereby the system is sized to provide the desired throughput, based upon its own system operating parameters.
There is a need in the art for cost effective dewatering systems, such as for a portable, hatch accessible, manually loadable, high throughput industrial fluid dewatering system that maintains the advantages of non-portable, non-hatch accessible, non-manually loadable vacuum dehydration industrial fluid dewatering systems of the prior art.